locale

LOCALE(7)                  Linux Programmer's Manual                 LOCALE(7)



NAME
       locale - description of multilanguage support

SYNOPSIS
       #include <locale.h>

DESCRIPTION
       A locale is a set of language and cultural rules.  These cover aspects
       such as language for messages, different character sets, lexicographic
       conventions, and so on.  A program needs to be able to determine its
       locale and act accordingly to be portable to different cultures.

       The header <locale.h> declares data types, functions and macros which
       are useful in this task.

       The functions it declares are setlocale(3) to set the current locale,
       and localeconv(3) to get information about number formatting.

       There are different categories for locale information a program might
       need; they are declared as macros.  Using them as the first argument to
       the setlocale(3) function, it is possible to set one of these to the
       desired locale:

       LC_ADDRESS (GNU extension, since glibc 2.2)
              Change settings that describe the formats (e.g., postal
              addresses) used to describe locations and geography-related
              items.  Applications that need this information can use
              nl_langinfo(3) to retrieve nonstandard elements, such as
              _NL_ADDRESS_COUNTRY_NAME (country name, in the language of the
              locale) and _NL_ADDRESS_LANG_NAME (language name, in the
              language of the locale), which return strings such as
              "Deutschland" and "Deutsch" (for German-language locales).
              (Other element names are listed in <langinfo.h>.)

       LC_COLLATE
              This category governs the collation rules used for sorting and
              regular expressions, including character equivalence classes and
              multicharacter collating elements.  This locale category changes
              the behavior of the functions strcoll(3) and strxfrm(3), which
              are used to compare strings in the local alphabet.  For example,
              the German sharp s is sorted as "ss".

       LC_CTYPE
              This category determines the interpretation of byte sequences as
              characters (e.g., single versus multibyte characters), character
              classifications (e.g., alphabetic or digit), and the behavior of
              character classes.  On glibc systems, this category also
              determines the character transliteration rules for iconv(1) and
              iconv(3).  It changes the behavior of the character handling and
              classification functions, such as isupper(3) and toupper(3), and
              the multibyte character functions such as mblen(3) or wctomb(3).

       LC_IDENTIFICATION (GNU extension, since glibc 2.2)
              Change settings that relate to the metadata for the locale.
              Applications that need this information can use nl_langinfo(3)
              to retrieve nonstandard elements, such as
              _NL_IDENTIFICATION_TITLE (title of this locale document) and
              _NL_IDENTIFICATION_TERRITORY (geographical territory to which
              this locale document applies), which might return strings such
              as "English locale for the USA" and "USA".  (Other element names
              are listed in <langinfo.h>.)

       LC_MONETARY
              This category determines the formatting used for monetary-
              related numeric values.  This changes the information returned
              by localeconv(3), which describes the way numbers are usually
              printed, with details such as decimal point versus decimal
              comma.  This information is internally used by the function
              strfmon(3).

       LC_MESSAGES
              This category affects the language in which messages are
              displayed and what an affirmative or negative answer looks like.
              The GNU C library contains the gettext(3), ngettext(3), and
              rpmatch(3) functions to ease the use of this information.  The
              GNU gettext family of functions also obey the environment
              variable LANGUAGE (containing a colon-separated list of locales)
              if the category is set to a valid locale other than "C".  This
              category also affects the behavior of catopen(3).

       LC_MEASUREMENT (GNU extension, since glibc 2.2)
              Change the settings relating to the measurement system in the
              locale (i.e., metric versus US customary units).  Applications
              can use nl_langinfo(3) to retrieve the nonstandard
              _NL_MEASUREMENT_MEASUREMENT element, which returns a pointer to
              a character that has the value 1 (metric) or 2 (US customary
              units).

       LC_NAME (GNU extension, since glibc 2.2)
              Change settings that describe the formats used to address
              persons.  Applications that need this information can use
              nl_langinfo(3) to retrieve nonstandard elements, such as
              _NL_NAME_NAME_MR (general salutation for men) and
              _NL_NAME_NAME_MS (general salutation for women) elements, which
              return strings such as "Herr" and "Frau" (for German-language
              locales).  (Other element names are listed in <langinfo.h>.)

       LC_NUMERIC
              This category determines the formatting rules used for
              nonmonetary numeric values—for example, the thousands separator
              and the radix character (a period in most English-speaking
              countries, but a comma in many other regions).  It affects
              functions such as printf(3), scanf(3), and strtod(3).  This
              information can also be read with the localeconv(3) function.

       LC_PAPER (GNU extension, since glibc 2.2)
              Change the settings relating to the dimensions of the standard
              paper size (e.g., US letter versus A4).  Applications that need
              the dimensions can obtain them by using nl_langinfo(3) to
              retrieve the nonstandard _NL_PAPER_WIDTH and _NL_PAPER_HEIGHT
              elements, which return int values specifying the dimensions in
              millimeters.

       LC_TELEPHONE (GNU extension, since glibc 2.2)
              Change settings that describe the formats to be used with
              telephone services.  Applications that need this information can
              use nl_langinfo(3) to retrieve nonstandard elements, such as
              _NL_TELEPHONE_INT_PREFIX (international prefix used to call
              numbers in this locale), which returns a string such as "49"
              (for Germany).  (Other element names are listed in
              <langinfo.h>.)

       LC_TIME
              This category governs the formatting used for date and time
              values.  For example, most of Europe uses a 24-hour clock versus
              the 12-hour clock used in the United States.  The setting of
              this category affects the behavior of functions such as
              strftime(3) and strptime(3).

       LC_ALL All of the above.

       If the second argument to setlocale(3) is an empty string, "", for the
       default locale, it is determined using the following steps:

       1. If there is a non-null environment variable LC_ALL, the value of
          LC_ALL is used.

       2. If an environment variable with the same name as one of the
          categories above exists and is non-null, its value is used for that
          category.

       3. If there is a non-null environment variable LANG, the value of LANG
          is used.

       Values about local numeric formatting is made available in a struct
       lconv returned by the localeconv(3) function, which has the following
       declaration:

           struct lconv {

               /* Numeric (nonmonetary) information */

               char *decimal_point;     /* Radix character */
               char *thousands_sep;     /* Separator for digit groups to left
                                           of radix character */
               char *grouping;     /* Each element is the number of digits in
                                      a group; elements with higher indices
                                      are further left.  An element with value
                                      CHAR_MAX means that no further grouping
                                      is done.  An element with value 0 means
                                      that the previous element is used for
                                      all groups further left. */

               /* Remaining fields are for monetary information */

               char *int_curr_symbol;   /* First three chars are a currency
                                           symbol from ISO 4217.  Fourth char
                                           is the separator.  Fifth char
                                           is '\0'. */
               char *currency_symbol;   /* Local currency symbol */
               char *mon_decimal_point; /* Radix character */
               char *mon_thousands_sep; /* Like thousands_sep above */
               char *mon_grouping;      /* Like grouping above */
               char *positive_sign;     /* Sign for positive values */
               char *negative_sign;     /* Sign for negative values */
               char  int_frac_digits;   /* International fractional digits */
               char  frac_digits;       /* Local fractional digits */
               char  p_cs_precedes;     /* 1 if currency_symbol precedes a
                                           positive value, 0 if succeeds */
               char  p_sep_by_space;    /* 1 if a space separates
                                           currency_symbol from a positive
                                           value */
               char  n_cs_precedes;     /* 1 if currency_symbol precedes a
                                           negative value, 0 if succeeds */
               char  n_sep_by_space;    /* 1 if a space separates
                                           currency_symbol from a negative
                                           value */
               /* Positive and negative sign positions:
                  0 Parentheses surround the quantity and currency_symbol.
                  1 The sign string precedes the quantity and currency_symbol.
                  2 The sign string succeeds the quantity and currency_symbol.
                  3 The sign string immediately precedes the currency_symbol.
                  4 The sign string immediately succeeds the currency_symbol. */
               char  p_sign_posn;
               char  n_sign_posn;
           };

   POSIX.1-2008 extensions to the locale API
       POSIX.1-2008 standardized a number of extensions to the locale API,
       based on implementations that first appeared in version 2.3 of the GNU
       C library.  These extensions are designed to address the problem that
       the traditional locale APIs do not mix well with multithreaded
       applications and with applications that must deal with multiple
       locales.

       The extensions take the form of new functions for creating and
       manipulating locale objects (newlocale(3), freelocale(3), duplocale(3),
       and uselocale(3)) and various new library functions with the suffix
       "_l" (e.g., toupper_l(3)) that extend the traditional locale-dependent
       APIs (e.g., toupper(3)) to allow the specification of a locale object
       that should apply when executing the function.

ENVIRONMENT
       The following environment variable is used by newlocale(3) and
       setlocale(3), and thus affects all unprivileged localized programs:

       LOCPATH
              A list of pathnames, separated by colons (':'), that should be
              used to find locale data.  If this variable is set, only the
              individual compiled locale data files from LOCPATH and the
              system default locale data path are used; any available locale
              archives are not used (see localedef(1)).  The individual
              compiled locale data files are searched for under subdirectories
              which depend on the currently used locale.  For example, when
              en_GB.UTF-8 is used for a category, the following subdirectories
              are searched for, in this order: en_GB.UTF-8, en_GB.utf8, en_GB,
              en.UTF-8, en.utf8, and en.

FILES
       /usr/lib/locale/locale-archive
              Usual default locale archive location.

       /usr/lib/locale
              Usual default path for compiled individual locale files.

CONFORMING TO
       POSIX.1-2001.

SEE ALSO
       iconv(1), locale(1), localedef(1), catopen(3), gettext(3), iconv(3),
       localeconv(3), mbstowcs(3), newlocale(3), ngettext(3), nl_langinfo(3),
       rpmatch(3), setlocale(3), strcoll(3), strfmon(3), strftime(3),
       strxfrm(3), uselocale(3), wcstombs(3), locale(5), charsets(7),
       unicode(7), utf-8(7)

COLOPHON
       This page is part of release 5.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux                             2019-03-06                         LOCALE(7)